L1 Testing and Cert

So I'm going for my L1 cert soon. I know there is a written test and the launch. Our local HPR club is out of season till the fall. I'd like to attempt my cert at Southern Thunder. What do I need to do? I'm planning to use a PSII kit with an H128. I already have the 29/180 case with closures. The rocket is mid build right now.

So the big question is the test. What, how and where?

Kruegon said:

So I'm going for my L1 cert soon. I know there is a written test and the launch. Our local HPR club is out of season till the fall. I'd like to attempt my cert at Southern Thunder. What do I need to do? I'm planning to use a PSII kit with an H128. I already have the 29/180 case with closures. The rocket is mid build right now.

So the big question is the test. What, how and where?

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The L1 cert does not involve a written test, at least for NAR it doesn't, and I don't think there is one for Tripoli either. There is some paperwork with a checklist that the person signing off the cert needs to fill out, and you should probably review that. But it's not really a test. Get it at the NAR website.

You should be able to answer questions about the rocket and the flight you are planning --- where's the CG and CP, what's the weight, what's the motor, how high do you expect it to go, what's your delay for motor eject and how did you determine it? Things like that. You might be asked a few question about how you built it.

No written for L1. Build, fly on an H or I, and recover undamaged. Know where your CP and CG are. That's about it --at least for Tripoli... Pretty sure NAR is the same.

L2 has a written, though...


Later!

--Coop

ThirstyBarbarian said:

You should be able to answer questions about the rocket and the flight you are planning --- where's the CG and CP, what's the weight, what's the motor, how high do you expect it to go, what's your delay for motor eject and how did you determine it? Things like that. You might be asked a few question about how you built it.

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Yes, these... but you should know these before every flight anyways...


-----G

I will admit that I'd love to learn how to properly calculate CP without using a computer program. Of course CG is easy. Any particular person that has to oversee my flight? As it'll be at southern thunder, I expect there will be several cert flights.

Coop said:

Yes, these... but you should know these before every flight anyways...


-----G

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Agreed! I just wanted to point it out. For most rockets up through MPR, you can build the kit and fly the recommended motors printed on the packaging and have a successful flight without really knowing the expected altitude or how the recommended delay was determined. Once you get into HPR, you need to start calculating these things yourself.

Kruegon said:

I will admit that I'd love to learn how to properly calculate CP without using a computer program. Of course CG is easy. Any particular person that has to oversee my flight? As it'll be at southern thunder, I expect there will be several cert flights.

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I believe you need two NAP HPR certified members to witness the launch and the safe recovery. I think that drops to one if the person is L2 or L3. They sign off on your form. It is good practice to have these people lined up and ready to help before you get to the launch. Have them review your rocket and motor at the launch. They may want to see you build your Aerotech motor if you are using one of those.

And go to the NAR site and print off several copies of the certification paperwork so you can be sure you have the right forms.

Contact the host (club), and explain you'd like to certify L1 with them on such and such a date. They may tell you to speak with a specific person at the field, or place you in contact with them. Relax, enjoy the flight, and have someone else run the camera.


Later!

--Coop

Kruegon said:

I will admit that I'd love to learn how to properly calculate CP without using a computer program.

...

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Two ways to calculate Cp:

the cardboard cutout -

https://www.nar.org/NARTS/TR13.html
https://www.ret-erau.com/Modules/2011/Blinn/Module3/Center_of_Lateral_Area_Lab.pdf

do the math with the Barrowman equations -

https://my.execpc.com/~culp/rockets/Barrowman.html

If at all possible I would go meet the folks you'll be flying with before your cert attempt. Nothing beats a little face time and getting to know some fellow enthusiasts (other than your TRF buddies of course).

Kruegon said:

I will admit that I'd love to learn how to properly calculate CP without using a computer program. Of course CG is easy. Any particular person that has to oversee my flight? As it'll be at southern thunder, I expect there will be several cert flights.

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Using a program like OpenRocket is fine. Use the program to find the CP for your design. Weigh the finished rocket without the motor and balance it to find the CG, and then do a mass override and CG override in your simulator program. If youve changed the chute size, change it in the program too. Now you have an accurate representation of your rocket as built.

Next, select the motors you want to use and run the simulations. They will tell you the projected altitude and optimal delays for apogee deployments. Set your delays in the simulation as close as you can get to optimal, usually a little bit short or long. Rerun your sims and see if the deployment speed is acceptable. Look for any other potential issues, like low speed off the rail. Does adding the motor shift your stability?

What I did was to print a screenshot of my OR sims for various motors and showing the rocket design with CP and CG displayed. I also put some masking tape on the rocket so I could temporarily mark the CP, CG without a motor, and CG with a motor right on the rocket. Having the sims printed out let me show that the rocket would be stable, have good speed off the rail, fly to a projected altitude I was comfortable with, deploy near apogee at a reasonable speed, and descend at a safe rate.

I agree that it is a good idea to contact the club first and get in contact with the person who will witness your flight and sign you off. Also, be sure to get your NAR membership! You'll need your NAR number. If you are cutting it close and don't have your card yet, it's not the number on your confirmation email --- I had to call NAR to get mine.

If you've never flown the rocket before, give yourself time to put it up once on a G motor before the cert flight.

No test - that is only L2 for both organizations.
A single L2 or L3 NAR member can witness your flight or 2 L1 NAR Members can witness, I believe TRA is the same. Eventful and fun but nothing to stress over, when I took my test it was my first launch and everyone is very helpful. Also if you pass you can buy more motors that day and fly again.

Nick@JET said:

Also if you pass you can buy more motors that day and fly again.

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True! And that's a good reason to sim a few different motors beforehand. If you pass the cert flight, you can move immediately to the "Open Your Wallet" part of HPR and go to the vendor trailer for some Victory Lap motors! Woohoo!

Good luck, and more importantly, have fun! Think of it as a mid-power launch with a little more kick.

Are you doing Tripoli or NAR?

Others have explained NAR....if Tripoli, just make sure you join first, have your paperwork & membership #.

Either a club prefect or TAP [any prefect or TAP] must witness the flight.
Bring it back to them after recovery & if it can be flown again without repair [minor dings OK] you pass. I & most TAP's carry cert paperwork with us to all launches...just in case . But it would be wise to contact prefect ahead of time & ask him to bring paperwork & see if he has time to witness flight.

OR you could just print this form & bring it with you. View attachment UniversalCertificationForm.pdf

ThirstyBarbarian said:

I agree that it is a good idea to contact the club first and get in contact with the person who will witness your flight and sign you off. Also, be sure to get your NAR membership! You'll need your NAR number. If you are cutting it close and don't have your card yet, it's not the number on your confirmation email --- I had to call NAR to get mine.

If you've never flown the rocket before, give yourself time to put it up once on a G motor before the cert flight.

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All good advice. Just a make sure if you use a G motor that the rocket isn't marginal on the motor if it is go straight to the H, I learned that the hard way, the sim's said the G was good and they were right, but it left no room for a bonus delay, that Crayon will never fly again as the parachute deployed the same distance off the ground as the shock cord had length.

I also put some masking tape on the rocket so I could temporarily mark the CP, CG without a motor, and CG with a motor right on the rocket.

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Another way to do this is put a break in the paint at the CP location. Then you have a permanent CP mark that you can't screw up measuring in the field, and you can do the measuring in a controlled environment. Cheeto Dust is black aft of the CP and orange forward. CG can easily be determined in the field.

One other thing that's helpful is to know your motors' thrust right at ignition. My L1 cert witness wanted to make sure that I had 5:1 thrust:weight off the pad. I was using a longburn motor, so it might not be an issue with a more typical motor.

Also, at least for TRA, you must assemble the motor in the presence of the person doing the cert.

I'm going to join this Friday. I am very torn to be honest. Our low alt club (3650' waiver) is NAR. Our high alt club (30k waiver) is TRA. And I can't afford both clubs. This should easily be a no brainier for HPR, but there is a catch.

I've slowly started the efforts towards a model rocket group in my immediate area. Group, not club. The idea is to garner interest in rocketry at the school, church, scout and community levels. It's mostly about supplying info and guidance right now. Eventually I'd like for us to be able to do group launches. I may have a field. I have most of the equipment we'll need.

Once we start launching, we have 3 options. Start a club. Not my first choice. Fly as a subsidiary/alternative launch under the NAR group. Or fly as a subsidiary/alternative launch under the TRA group.

Both groups welcome the other group members. And we'll be concentrating on LPR and MPR only. I have no plans to request a waiver for that field.

With that in mind, what group should I look at joining? Originally it was going to be TRA. The prefect is holding an I285 for me since I'm not cert yet. But the NAR flies year round where TRA flies late fall to early spring. Oh the decisions. Advice is welcome.

Kruegon said:

I will admit that I'd love to learn how to properly calculate CP without using a computer program. Of course CG is easy. Any particular person that has to oversee my flight? As it'll be at southern thunder, I expect there will be several cert flights.

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ROCKSIM does it for you

AfterBurners said:

ROCKSIM does it for you

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Umm RockSim is a computer program though lol. I'm talking about expanding my knowledge. lol

That's a tough choice, if you cert in one organization, when you join the other, your grandfathered at your current cert level. Are you planning on assisting someone with a Jr. cert... then NAR (they have the Jr. HPR program). Either organization is good.
Kruegon's signature soon to say... NAR L1 2015....L2 2016 ...TRA L1,L2 2016...both L3 2017

Kruegon said:

I will admit that I'd love to learn how to properly calculate CP without using a computer program. Of course CG is easy. Any particular person that has to oversee my flight? As it'll be at southern thunder, I expect there will be several cert flights.

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Kruegon,
Read the link below. It may seem confusing at first but work through the examples and you should be able to calculate Cp for your own rockets.

https://www2.estesrockets.com/pdf/TIR-33_Center_of_Pressure.pdf

Thanks Jeff. I'll give it a try against my rocket and see how it compares to RockSim and OpenRocket.

Kruegon said:

Both groups welcome the other group members. And we'll be concentrating on LPR and MPR only. I have no plans to request a waiver for that field.

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Having been a TRA member for 12 years, and involved in some NAR events, if you are only going to do LPR and MPR (class 1), I would recommend going with NAR.

The reason both organizations have thrived over the years is they don't really compete with each other. The NAR focus is LPR and contests while the TRA focus is HPR and EX. Both org. overlap some, but the TRA club I fly with has five 1/8" and 3/16" rods for LPR and 15 1010 & 1515 pads and a unistrut trailer launcher for HPR, the NAR club near me sets up 15 - 20 LPR/MPR pads and one 1010 HPR rail. Neither club is any better then the other, it's just a matter of where their focus is.

You should go with the organization that most closely matches your priorities and it sounds like NAR would be the better match.